On Fri, Sep 10, 2021 at 08:36:26AM -0700, Daniele Ceraolo Spurio wrote:
> Now that all the pieces are in place we can add a description of how the
> feature works. Also modify the comments in struct intel_pxp into
> kerneldoc.
>
> v2: improve doc (Rodrigo)
>
> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> ---
> Documentation/gpu/i915.rst | 8 ++++
> drivers/gpu/drm/i915/pxp/intel_pxp.c | 28 +++++++++++++
> drivers/gpu/drm/i915/pxp/intel_pxp_types.h | 47 ++++++++++++++++------
> 3 files changed, 71 insertions(+), 12 deletions(-)
>
> diff --git a/Documentation/gpu/i915.rst b/Documentation/gpu/i915.rst
> index 101dde3eb1ea..78ecb9d5ec20 100644
> --- a/Documentation/gpu/i915.rst
> +++ b/Documentation/gpu/i915.rst
> @@ -471,6 +471,14 @@ Object Tiling IOCTLs
> .. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_tiling.c
> :doc: buffer object tiling
>
> +Protected Objects
> +-----------------
> +
> +.. kernel-doc:: drivers/gpu/drm/i915/pxp/intel_pxp.c
> + :doc: PXP
> +
> +.. kernel-doc:: drivers/gpu/drm/i915/pxp/intel_pxp_types.h
> +
> Microcontrollers
> ================
>
> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp.c b/drivers/gpu/drm/i915/pxp/intel_pxp.c
> index 97c6368fddc3..5610634f8929 100644
> --- a/drivers/gpu/drm/i915/pxp/intel_pxp.c
> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp.c
> @@ -11,6 +11,34 @@
> #include "gt/intel_context.h"
> #include "i915_drv.h"
>
> +/**
> + * DOC: PXP
> + *
> + * PXP (Protected Xe Path) is a feature available in Gen12 and newer platforms.
> + * It allows execution and flip to display of protected (i.e. encrypted)
> + * objects. The SW support is enabled via the CONFIG_DRM_I915_PXP kconfig.
> + *
> + * Objects can opt-in to PXP encryption at creation time via the
> + * I915_GEM_CREATE_EXT_PROTECTED_CONTENT create_ext flag. For objects to be
> + * correctly protected they must be used in conjunction with a context created
> + * with the I915_CONTEXT_PARAM_PROTECTED_CONTENT flag. See the documentation
> + * of those two uapi flags for details and restrictions.
> + *
> + * Protected objects are tied to a pxp session; currently we only support one
> + * session, which i915 manages and whose index is available in the uapi
> + * (I915_PROTECTED_CONTENT_DEFAULT_SESSION) for use in instructions targeting
> + * protected objects.
> + * The session is invalidated by the HW when certain events occur (e.g.
> + * suspend/resume). When this happens, all the objects that were used with the
> + * session are marked as invalid and all contexts marked as using protected
> + * content are banned. Any further attempt at using them in an execbuf call is
> + * rejected, while flips are converted to black frames.
> + *
> + * Some of the PXP setup operations are performed by the Management Engine,
> + * which is handled by the mei driver; communication between i915 and mei is
> + * performed via the mei_pxp component module.
> + */
> +
> /* KCR register definitions */
> #define KCR_INIT _MMIO(0x320f0)
>
> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp_types.h b/drivers/gpu/drm/i915/pxp/intel_pxp_types.h
> index ae24064bb57e..73ef7d1754e1 100644
> --- a/drivers/gpu/drm/i915/pxp/intel_pxp_types.h
> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp_types.h
> @@ -16,42 +16,65 @@
> struct intel_context;
> struct i915_pxp_component;
>
> +/**
> + * struct intel_pxp - pxp state
> + */
> struct intel_pxp {
> + /**
> + * @pxp_component: i915_pxp_component struct of the bound mei_pxp
> + * module. Only set and cleared inside component bind/unbind functions,
> + * which are protected by &tee_mutex.
> + */
> struct i915_pxp_component *pxp_component;
> + /**
> + * @pxp_component_added: track if the pxp component has been added.
> + * Set and cleared in tee init and fini functions respectively.
> + */
> bool pxp_component_added;
>
> + /** @ce: kernel-owned context used for PXP operations */
> struct intel_context *ce;
>
> - /*
> + /** @arb_mutex: protects arb session start */
> + struct mutex arb_mutex;
> + /**
> + * @arb_is_valid: tracks arb session status.
> * After a teardown, the arb session can still be in play on the HW
> * even if the keys are gone, so we can't rely on the HW state of the
> * session to know if it's valid and need to track the status in SW.
> */
> - struct mutex arb_mutex; /* protects arb session start */
> bool arb_is_valid;
>
> - /*
> - * Keep track of which key instance we're on, so we can use it to
> - * determine if an object was created using the current key or a
> + /**
> + * @key_instance: tracks which key instance we're on, so we can use it
> + * to determine if an object was created using the current key or a
> * previous one.
> */
> u32 key_instance;
>
> - struct mutex tee_mutex; /* protects the tee channel binding */
> + /** @tee_mutex: protects the tee channel binding and messaging. */
> + struct mutex tee_mutex;
>
> - /*
> - * If the HW perceives an attack on the integrity of the encryption it
> - * will invalidate the keys and expect SW to re-initialize the session.
> - * We keep track of this state to make sure we only re-start the arb
> - * session when required.
> + /**
> + * @hw_state_invalidated: if the HW perceives an attack on the integrity
> + * of the encryption it will invalidate the keys and expect SW to
> + * re-initialize the session. We keep track of this state to make sure
> + * we only re-start the arb session when required.
> */
> bool hw_state_invalidated;
>
> + /** @irq_enabled: tracks the status of the kcr irqs */
> bool irq_enabled;
> + /**
> + * @termination: tracks the status of a pending termination. Only
> + * re-initialized under gt->irq_lock and completed in &session_work.
> + */
> struct completion termination;
>
> + /** @session_work: worker that manages session events. */
> struct work_struct session_work;
> - u32 session_events; /* protected with gt->irq_lock */
> + /** @session_events: pending session events, protected with gt->irq_lock. */
> + u32 session_events;
> #define PXP_TERMINATION_REQUEST BIT(0)
> #define PXP_TERMINATION_COMPLETE BIT(1)
> #define PXP_INVAL_REQUIRED BIT(2)
> --
> 2.25.1
>
